Preheat your oven to 425 degrees, and line a baking sheet with parchment paper. Set aside.
In a large bowl, stir together the flour, baking powder, baking soda, sugar, and salt. Using a pastry blender or clean hands, cut the cold butter into your flour mixture until it has coarse crumbs of butter running throughout.
In a small bowl, whisk together the sour cream, heavy cream, vinegar, egg, and vanilla extract until combined. Pour the wet ingredients into the dry, and use a spatula to mix until a dough comes together. Turn your dough out onto a floured surface, and gently knead it until it just comes together, adding more flour if needed until the dough is not sticky, but still holds together. Pat the dough into a disc about 1/2-3/4 inch thick. Use a sharp knife to cut it like a pizza into 8 even scones.
Place your scones onto your prepared baking sheet spaced evenly. Brush the tops generously with cream, and sprinkle with the coarse sugar. Bake for 10-12 minutes, or until the scones are golden on top. Cool and enjoy!